Guidance for Industry and FDA Staff - Class II Special Controls Guidance Document: Hepatitis A Virus Serological Assays
Document issued on: February 9, 2006
For questions regarding this document contact Sally Hojvat, Ph.D., Division of Microbiology Devices at 301-796-5455 or by email: firstname.lastname@example.org.
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Table of Contents
Draft Guidance for Industry and FDA Staff
Class II Special Controls Guidance Document:
|Identified risk||Recommended mitigation measures|
|Improper patient management||Sections 7-10|
We recommend that you include the following in your device description:
- a description of the method that your device uses to detect HAV-specific IgM, IgG, or total antibodies (e.g., enzyme immunoassay)
- a description of the reagent components included with the kit
- information on the antibodies detected or measured
- a clear explanation for the specific controls and calibrators to be used in the assay
- a description of the primary purpose for the quality control material
In your description of reagent components, you should provide the antigen source and explain how it was characterized. If a recombinant antigen is used, you should supply specific information concerning the specific HAV epitopes present on the antigen and specific information for antigen characterization. For monoclonal antibodies, you should give specific information concerning HAV epitopes detected by the assay, and provide appropriate antibody characterization.
General Study Recommendations
We recommend that you test specimens from individuals that have been vaccinated against HAV. You should evaluate a baseline specimen (pre-vaccination) and a post-vaccination specimen collected no earlier than 4 weeks post vaccination from individuals aged two years and greater.5 In your study, you should include all vaccines that are currently U.S. licensed. If the assay’s capture antigen is different than the vaccine strain, you should explain why this will not produce a false negative result when testing for immunity due to vaccination. If the antigen used in the assay is the same strain, and has been treated in the same manner as the vaccine, the above testing will not be necessary [Ref. 7].
Specimen collection and handling conditions
We recommend that you substantiate statements in your labeling about specimen storage and transport by assessing whether the device can maintain acceptable performance (e.g., assay precision) over the storage times and temperatures recommended to users. For example, an appropriate study may include an analysis of aliquots stored under the conditions of time, temperature, or number of freeze/thaw cycles that you recommend to users of the device. We recommend that you state the criteria for an acceptable range of recoveries under the recommended storage and handling conditions [Ref. 8].
You should conduct internal precision testing (i.e., at the manufacturer’s site) in accordance with CLSI, EP5-A2 [Ref. 9]. Precision testing performed in accordance with CLSI, EP15-A2 [Ref. 10] should be conducted at three external sites.
We recommend that you characterize samples used for intra- and inter-assay precision testing according to guidelines provided in the CLSI, EP12-A [Ref. 11].
We recommend that you use patient samples, your assay calibrator(s), and the quality control materials that you supply or recommend for your device for this characterization. We recommend that you evaluate precision at relevant measurements, including levels near medical decision points and measurements near the limits of the reportable range.
We recommend that you include the following items in your 510(k):
- point estimates of the concentration for levels of anti-HAV
- sites at which the precision protocol was run
- number of days, runs, and observations
- number of sites and/or operators
- standard deviations of intra- and inter-assay precision with exact 95% confidence intervals
We recommend that you identify which factors (e.g., instrument calibration, reagent lots, and operators) were held constant and which were varied during the evaluation. Describe the computational methods, if they are different from that described in CLSI EP15-A2 and CLSI EP5-A2.
If your assay requires, or you recommend, automated instrumentation, we recommend that you perform the above-mentioned precision with three different instrument builds, i.e., different instrument serial numbers.
We recommend that you characterize the effects of potential interferents on assay performance. Examples of experimental designs, including guidelines for selecting interferents for testing, are described in detail in CSLI, EP7-A [Ref. 12]. Potential sources of interference can include compounds normally found in serum, such as triolein (triglycerides), hemoglobin, bilirubin, and serum albumin.
We recommend that you include the following items in your 510(k):
- types and levels of interferents tested
- levels of antibody in the sample, including a description of how the levels were determined
- number of replicates tested
- definition or method for computing interference
We recommend that you identify any observed trends in bias (i.e., negative or positive) and indicate the range of observed recoveries in the presence of the particular interferent. This approach is more informative than listing average recoveries alone. We recommend that you state your criteria or level for determining non-interference.
You may not need to perform additional interference testing with potential interferents of your assay that have already been identified in literature or by other sources. However, you may address additional potential interferents with appropriate citations in the labeling.
We recommend that you include data on assay specificity by measuring the cross reactivity of your device with antibodies to other relevant microorganisms. In particular, you should perform studies to characterize performance in the presence of antibodies to other viruses that cause hepatitis [e.g., Epstein Barr Virus (EBV), HBV, HCV, cytomegalovirus (CMV), rubeola virus, mumps virus, and varicella zoster virus (VZV)], and other microorganisms that cause hepatitis (e.g., Toxoplasma gondii). If your antigen is recombinant, we recommend that you provide cross-reactivity studies against the recombinant vector. For HAV IgM assays, we recommend that you include performance in the presence of such factors as rheumatoid factor, anti-nuclear antibodies, and human anti-mouse antibodies.
We recommend that you provide data to explain how your clinically relevant cut-off point was selected and established. You should provide information on the use of an equivocal zone for testing. If you believe an equivocal zone is inappropriate, you should provide an explanation for this, since there is not a confirmation assay for anti-HAV.
Other analytical studies
We recommend that you test seroconversion panels. The panels should incorporate specimens prior to the appearance of the analyte and, in the case of anti-HAV IgM, when the analyte begins to wane. Many of these panels are commercially available. If you use a commercial panel, we recommend that you reassess its reported reactivity with a legally marketed assay.
We recommend that you test against recognized standards for anti-HAV, e.g., Paul Ehrlich-Institute or World Health Organization (National Institute for Biological Standards and Control) standards, to determine the assay’s analytical sensitivity, i.e., limit of detection (LoD).
If a matrix other than serum is recommended, e.g., EDTA or sodium heparin anticoagulated plasma, you should provide information demonstrating that there is minimal (or no) assay effect when these anticoagulants are compared to serum. We recommended that this testing be done in a manner analogous to the evaluation described for method comparison in CLSI, EP9-A2 [Ref. 13] and the World Health Organization’s, Use of Anticoagulants in Diagnostic Laboratory Investigations [Ref. 14].
We recommend that you establish the prevalence of HAV antibodies in a normal population (healthy individuals without symptoms) using the specified cut-off. You should test a statistically significant number of samples that are consistent with the current U.S. census for age, gender, and ethnicity. Since HAV infection occurs sporadically within the U.S., with more cases being reported from the Western U.S. (Figure 1), we suggest that prevalence studies be conducted in the Eastern U.S. (low prevalence) and the Western U.S (high prevalence). You should provide results based on your device. For Expected Values testing, results based on other devices are not needed. We recommend that you summarize the distribution of the population according to age groups (in decades), gender, geographical area, and the number of positive, negative, and equivocal results. We recommend that blood donors not be used for this study.
Figure 1. Centers for Disease Control and Prevention. Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1999;48(No. RR-12):p. 7.
We recommend that you evaluate your assay at three sites, one of which may be the manufacturer’s site. We recommend that you assess performance in the testing environment where the device will ultimately be used (i.e., clinical laboratory) by individuals who will use the test in clinical practice (e.g., trained technologists). We recommend that you initially analyze data from each study site separately to evaluate any inter-site variation and include results of the analysis in the 510(k) summary report. It may be possible to pool clinical study results from the individual sites in the package insert if you can demonstrate that there are no significant differences in the results or populations among sites. Before initiating any clinical study, you may consult the Division of Microbiology Devices.
So that we can best interpret acceptance criteria or data summaries during the review, we recommend that you provide appropriate specific information concerning protocols. This information is also necessary to aid users in interpreting information in your labeling. For example, when referring to CLSI protocols or guidelines, we recommend that you indicate which specific aspects of the protocols or guidelines you followed.
Detectability and Comparative Performance
We recommend that you determine the detectability of antibody to HAV by comparing test performance with a legally marketed device (predicate device) or by testing against an appropriate algorithm that will diagnose HAV acute and past infection. We recommend prospective collection of specimens from individuals with signs and symptoms of acute hepatitis, e.g., hepatology or gastroenterology clinic patients. You may supplement these studies with well-characterized specimens obtained from repository banks. This specimen characterization should include information supporting sample integrity, appropriate selection, and clinical laboratory testing results. You should consider and address sources of bias. Since acute HAV prevalence is relatively low in the U.S., reactive specimens, especially those specimens containing anti-HAV IgM, may be obtained from non-U.S. sources. The information you provide concerning sample characterization of non-U.S. specimens should be the same as that for specimens from the U.S.
Sample Selection, Inclusion and Exclusion Criteria
We recommend that you evaluate samples from the intended use population (i.e., individuals with signs and symptoms of hepatitis) in a prospective study, and provide a clear description of how the samples were selected, including reasons that samples were excluded.
Appropriate sample size of the indicated population depends on factors such as precision, interference, and other performance characteristics of the test. We recommend that you provide a statistical justification to support the sample size of the study population.
Presentation of Results
We recommend that you provide line data for all studies. You may supply this information electronically using Microsoft EXCEL, delimited text files, or SAS files.
The premarket notification should include labeling in sufficient detail to satisfy the requirements of 21 CFR 807.87(e). Although final labeling is not required for 510(k) clearance, final labeling must comply with the requirements of 21 CFR part 801 and 21 CFR 809.10 before a medical device is introduced into interstate commerce.
The following suggestions are aimed at assisting you in submitting labeling that satisfies these requirements and preparing final labeling.
Directions for Use
You should provide clear and concise instructions that delineate the technological features of the specific device and how the device is to be used on patients. Instructions should encourage local/institutional training programs designed to familiarize users with the features of the device and how to use it in a safe and effective manner.
We recommend that you provide a description of quality control recommendations in the labeling and specify what your quality control material will measure.
Precautions for Use
We recommend that you address issues concerning safe use of your assay with statements in the labeling, such as the following:
Human samples and blood-derived products may be routinely processed with minimum risk using the procedures described. Human source components of this device were tested and found negative for anti HIV (types 1 and 2), anti-HCV, and HBsAg by FDA recommended (approved/licensed) tests. Because no test method can offer complete assurance that laboratory specimens do not contain HIV, hepatitis B virus, or other infectious agents, specimens should be handled at the Biosafety Level 2 (BL2) as recommended for any potentially infectious human serum or blood specimen in the CDC NIH manual, Biosafety in Microbiological and Biomedical Laboratories, 3rd Edition, 1993 and CLSI Approved Guideline M29-A, Protection of Laboratory Workers from Instrument Biohazards and Infectious Disease Transmitted by Blood, Body Fluids, and Tissue.
Precautions for Interpretations
We recommend that you address issues concerning patient safety with statements in the labeling, such as the following:
Assay results should be interpreted only in the context of other clinical laboratory findings and the total clinical status of the individual. It has been shown that a viremic window exists with individuals infected with HAV where the individual may be symptomatic for hepatitis, but anti-HAV IgM nonreactive [Ref. 15].
|||Devalle S, de Paula VS, de Oliveira JM, et al. 2003. Hepatitis A virus infection in hepatitis C Brazilian patients, J Infect. Aug;47(2):125-128.|
|||Koff RS, 2001. Risks associated with hepatitis A and hepatitis B in patients with hepatitis C, J Clin Gastroenterol. Jul;33(1):20-26.|
|||Vento S, 2000. Fulminant hepatitis associated with hepatitis A virus superinfection in patients with chronic hepatitis C, J Viral Hepat. May;7 Suppl 1:7-8.|
|||J.T. Stapleton, 1995. Host immune response to hepatitis A virus. Journal Infect Dis. 171(S1):S9-S14.|
|||F.B. Hollinger and S.U. Emerson, 2001. Hepatitis A virus. Fields Virology 4th ed. D.M. Knipe et al., eds. Lippincott Williams & Wilkins, Phila., 799-840.|
|||CDC, Epidemiology Program Office, Division of Public Health Surveillance and Informatics, Nationally Notifiable Infectious Diseases.|
|||Poltera A, Herzog C, 2001. Vaccine-induced antibodies assessed by commercial test kits, the case of the Rubini mumps and the Edmonston-Zagreb measles vaccine strains, Vaccine 19:396-398.|
|||Clinical and Laboratory Standards Institute (CLSI). Procedures for the Handling and Processing of Blood Specimens; Approved Guideline—Third Edition. CLSI document H18-A3 (ISBN 1-56238-555-0). CLSI, 940 West Valley Road, Suite 1400, Wayne, Pennsylvania 19087-1898 USA, 2004.|
|||Clinical and Laboratory Standards Institute (CLSI). Evaluation of Precision Performance of Quantitative Methods; Approved Guideline-Second Edition. CLSI document EP5-A2 (ISBN 1-56238-000-0). CLSI, 940 West Valley Road, Suite 1400, Wayne, Pennsylvania 19087-1898 USA, 2004.|
|||Clinical and Laboratory Standards Institute (CLSI). User Verification of Performance for Precision and Trueness; Approved Guideline. CLSI document EP15-A2 [ISBN 1-56238-574-7]. CLSI, 940 West Valley Road, Suite 1400, Wayne, Pennsylvania 19087-1898 USA, 2005.|
|||Clinical and Laboratory Standards Institute (CLSI). User Protocol for Evaluation of Qualitative Test Performance; Approved Guideline. CLSI document EP12-A (ISBN 1-56238-468-6). CLSI, 940 West Valley Road, Suite 1400, Wayne, Pennsylvania 19087-1898 USA, 2002.|
|||Clinical and Laboratory Standards Institute (CLSI). Interference Testing in Clinical Chemistry; Approved Guideline. CLSI document EP7-A (ISBN 1-56238-468-6). CLSI, 940 West Valley Road, Suite 1400, Wayne, Pennsylvania 19087-1898 USA, 2002.|
|||Clinical and Laboratory Standards Institute (CLSI). Method Comparison and Bias Estimation Using Patient Samples; Approved Guideline – Second Edition. CLSI document EP9-A2 (ISBN 1-56238-472-4). CLSI, 940 West Valley Road, Suite 1400, Wayne, Pennsylvania 19087, 2002.|
|||World Health Organization, Use of Anticoagulants in Diagnostic Laboratory Investigations, WHO/DIL/LAB/99.1 Rev.2.|
|||de Paula VS, Villar LM, Morais LM, et al., 2004. Detection of hepatitis A virus RNA in serum during the window period of infection, J Clin Virol. (29):254-259.|
1 Unlike other classification regulations in 21 CFR part 866, subpart D, which use the term “reagents” in their titles, FDA is using “assays” to refer to this device type because this term more accurately reflects the devices within this type.
2 Refer to Indications for Use Form (PDF File Size: 1.03MB).
3 If FDA makes a substantial equivalence determination based on acceptance criteria, the subject device should be tested and shown to meet these acceptance criteria before being introduced into interstate commerce.
4 See Required Elements for a Declaration of Conformity to a Recognized Standard (Screening Checklist for All Premarket Notification [510(K)] Submissions).
5 Due to the HAV vaccine’s high efficacy, there is not a recommendation to test post vaccination for vaccine efficacy. Pre-vaccination testing may be desired where anti-HAV prevalence is high and previous vaccination history is unknown. [Hepatitis A, Epidemiology and Prevention of Vaccine-Preventable Diseases, 8th Edition, National Immunization Program, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services.] Therefore, anti-HAV IgG and total antibody assays should demonstrate their ability to detect vaccine induced anti-HAV so that previously immunized individuals will not be revaccinated.